But, White said in an interview, "The majority of scientists said the data they were talking about for beneficial effects on health is very weak" and doesn't really support health claims for soy foods.
White and his associates have been studying diseases and aging in a group of Japanese-American men who volunteered for medical research in 1965. The Honolulu Heart Program began with 8,006 men born from 1900 through 1919. They were identified through World War II Selective Service registration records.
In comparing the dietary habits and health of the Japanese-American men in the study group between 1965 and 1993, White said the scientists found "a significant link between tofu consumption during midlife and loss of mental ability and even loss of brain weight."
The men were questioned about 27 foods and drinks, with data showing that those who ate more tofu were apt to have impaired mental ability, White said. Tofu was the only consistent link among the men, he said. The rate of brain impairment, which normally increases with age, also went up faster in the men who ate the most tofu, he said.
"The test results were about equivalent to what they would have been if they were five years older," he said. "Guys who ate none, their test scores were as though they were five years younger."
The brains of 300 men who died also were examined in a unique autopsy study conducted as part of the Honolulu aging project, White said. The 300 men didn't appear to have had any more strokes than the average person, and their blood vessels didn't look different.
"But what I did see was (that) the simple weight of the brain was lower," he said. Shrinkage occurs naturally with age, but atrophy progressed more rapidly in those men who had consumed more tofu, White said.